Heavy duty stretch forming machine



May 25, 1965 Filed Oct. 16, 1962 C. J. BATH HEAVY DUTY STRETCH FORMING MACHINE 6 SheesSheet l INVENIOR BY M y 5, 1965 c. J. BATH 3,184,948

HEAVY DUTY STRETCH FORMING MACHINE Filed Oct. 16, 1962 6 Sheets-Sheet 2 ,Q &

INVENTOR.

May 25, 1965 c. J. BATH HEAVY DUTY STRETCH FORMING MACHINE 6 Sheets-Sheet 3 Filed Oct. 16, 1962 MN m2 INVI'EZNZOR, M BY 74 May 25, 1965 c. J. BATH HEAVY DUTY STRETCH FORMING MACHINE 6 sheets-sk et 4 Filed 001:. 16, 1962 I INVENTOR. G 44 M BY J y 25, 1965 c. J. BATH 3,184,948

HEAVY DUTY STRETCH FORMING MACHINE Filed Oct. 16, 1962 6 Sheets-Sheet 5 y 25, 1965 c. J. BATH 3,184,948

HEAVY DUTY STRETCH FORMING MACHINE Filed Oct. 16, 1962 6 Sheets-Sheet 6 A 7701NE K United States Patent 3,184,948 HEAVY DUTY STRETCH FGRMENG MACHHQE Cyril .1'. Bath, (Ihagrin Falls, Ohio, assignor to The (:Jyril Bath Company, Solon, Ohio, a corporation of (lino Filed Oct. 16, 1962, Ser. No. 230,930 3 Claims. (Cl. 72-297) The present invention relates to stretch forming machines of the general character described in United States Letters Patent No. 2,514,830 of Cyril I. Bath, issued July 11, 1950, and particularly to a machine of this general character suitable for extra heavy duty, for example, for machines capable of exerting from 1,000 to 4,000 tons tension on a length of stock to stretch form it onto a side face die.

In the above entitled patent, the machine shown is one employing a turntable rotatable about an upright axis. A side face die is mounted on the turntable for rotation therewith about the upright axis. The stock is clamped at one end in fixed position relative to the die and at the other end to a stretch forming head which is yieldably urged away from the die by means of a hydraulic piston and cylinder assemblage during the rotation of the table for stretch forming the stock.

The present machine performs essentially the same function, but is so arranged that it can stretch form sheet metal stock of much greater thickness, width, and length than the stock heretofore stretch formed, and can exert on the stock a much greater total tension than is possible with machines heretofore existing. For handling such great forces in a manner to stretch form stock, substantial modifications in the machine described in the above entitled patent are necessary.

, The machine of the present invention is one in which the stretch forming assemblage moves along a planar track, and the turntable rotates about an axis which is parallel to the plane of the track and extends transversely of the track. The stretch head swings toward and away from the plane.

In the above entitled patent, the turntable is arranged with its axis generally normal to the plane of the path of the stretch forming head, and the stretch forming head swings parallel to the plane of its path transversely of the turntable axis.

The principal objects of the present invention are to provide, in a stretch forming machine, a new and improved turntable for resisting extremely high tension applied through the stock, improved means for mounting the dies thereon, and an improved stretch forming assemblage for tensioning the stock.

A more specific object is to provide bearings arranged for supporting the turntable at both ends of the die so as to reduce unbalanced loads on the turntable bearings and tilting of the turntable, and one of which is removable for permitting ready removal of the stock from the die and table.

Another specific object resides in the counterbalancing of the stock gripping head of the stretch forming assemblage for facilitating introduction of the stock margin thereinto and for more effective cooperation with the stock so as to relieve the stock from substantially all tensioning and binding forces other than the direct pull, endwise of the stock and tangentially of the die face, required for stretch forming the stock onto the side face of the die.

Various other objects and advantages of the present invention will become apparent from the following description, wherein reference is made to the drawings, in which:

FIG. 1a is a top plan view of the forward portion of a machine embodying the principles of the present invention;

FIG. lb is a top plan view of the rearward portion of the machine, the right end part of the front portion of FIG. 1a being duplicated therein for clearness in illustration;

FIG. 2a is a side elevation of the structure of FIG. 1a;

FIG. 2b is a side elevation of the structure illustrated in FIG. lb;

FIG. 3 is a vertical cross sectional view of the machine taken on the plane indicated by the line 3-3 in FIG. 2b, the turntable, driving mechanism therefor, and operators platform being omitted for clarity in illustration;

FIG. 4 is a vertical fragmentary sectional view through the turntable of the machine and a die thereon and is taken on the line 4-4 in FIG. 111;

FIG. 5 is a vertical fragmentary sectional view taken on the line 55 in FIG. 1a;

FIG. 6 is an enlarged fragmentary elevation, as viewed from the line 6--6 in FIG. 1a, of a portion of the carriage for the stretch forming head, showing the gripping jaws and parts of the supporting arms of the head;

FIG. 7 is a vertical fragmentary sectional View taken through the portion of the gripping head and one of its supporting arms, and is taken on line 7-7 in FIG. 1a, and

FIG. 8 is a diagrammatic side elevation of the turntable of the apparatus, showing a die of different shape than that of FIG. 4 mounted thereon.

Referring to the drawings, the machine comprises a frame indicated generally at 1, including a plurality of transverse base members 2 spaced apart laterally from each other endwise of the frame. The members 2 support rails 3 of a horizontal lower track which extends endwise of the frame. Mounted on the outer margins of the rails 3 are upright side frame members 4 which are reinforced by gussets 5 distributed along the length of the frame. At their upper ends the members 4 support the rails 6 of an upper track parallel to the lower track.

The stretch forming assemblage for applying tension to the stock comprises a carriage 10 which is supported at its rear by Wheels or rollers 11 which operate on the rails 6, respectively. At its forward end, the carriage is provided with downwardly extending brackets 12 carrying lower wheels or rollers 13 which normally operate on the rails 3, respectively. If the resultant tensioning force lifts the forward end of the carriage slightly, the wheels 13 engage and roll along the underside of the rails 6, respectively. Guide rollers 14 are mounted on the carriage and roll along the inner faces on the upper rails 6 for maintaining the carriage in proper alignment transversely of the tracks.

The carriage is provided with a rigid integral rib 15 which extends transversely of the carriage. A plurality of stretch forming piston and cylinder assemblages 16 are provided 101' yieldably urging the carriage in one direction along the tracks. Each assemblage 16 comprises a pinrality of cylinders 17 mounted on suitable trunnions 18 on the frame for rocking about an axis extending transversely of, and parallel to, the planes of the trackways. Each cylinder 17 carries a piston 19 having a piston rod 20. The forward end of each rod 20 is connected to the rib 15 of the carriage. Pressure fluid is supplied to the opposite ends of the cylinder 17 selectively through a suitable reversing valve 22 to which fluid is supplied by driven pump P driven by an electric motor M. T he supply of pressure fluid and its control may be conventional and forms no part of the present invention. A platform 23 with a control panel 24- is mounted on the carriage 10.

In order to grip the stock and apply tension thereto, a stretch head 30 is provided. The stretch head is supported by a plurality of parallel arms, indicated generally at 31. These arms are the same in form and function, hence only one will be described specifically. Each arm 31 comprises an outer sleeve 32 having at one end a bearing adapted to receive a rock shaft 33 which is common to all of the arms 31 and which is mounted on the carriage with its axis horizontal-and extending transversely of the tracks. Connected to each outer sleeve 32 is an inner sleeve 34. The connection between these sleeves is by upright tension bolts 35a and horizontal transverse tension bolts 35b, as more fully described in United States Letters Patent No. 3,052,118, issued September 4, 1962, to Perkins et al. and entitled, Load Cell and Combination Thereof with Stretch Forming Machine. As therein more fully described, a load cell 36 is connected at its ends to the sleeves 32 and 34-, one end being connected to the sleeve 34 and the other end beingconuected to the sleeve 32. With this arrangement, substantially only the stresses actually applied to the stock S itself are reflected by the load cell. The structure of the arms thus described is necessarily relatively heavy considering the forces to be applied thereto. Accordingly, all of the arms are tied rigidly together by cross tie members 33 and 39.

In order to relieve the stresses that would be imposed on the stock by the mere weight of the arms and heads themselves, a counterbalance 40 is provided on each arm. The counterbalance is comprised of depending brackets 41 I which extend from the associated arms at a location between the rock shaft 33 and stretchhead 30. Extending rearwardly and generally horizontally from each bracket.

41 is counterbalance weight support 42, on the outer end of which is mounted a counterbalancing weight 43. The weights may be adjusted along the length of the outer ends of the arm fora short distance. The weights are preferably sulficien-t to counterbalance the weight of the stretch head and the arms themselves, or may be slightly overbalanced so as to counterbalance partially the weight of the portion of the stock suspended between the head 3% and the turntable.

Mounted on the frame near one end ofthe trackway is the turntable 45 which, in the form illustrated, may be a heavy rugged shaft arranged with its axis horizontal and extending across the trackway, and therefore parallel to the rock shaft 33. The turntable 45 has one end mounted in suitable bearings 46 which are disposed one side of the trackway and are spaced apart from each other axially of the turntable 45. This end of the turntable 55 is provided with main driving gears 47 which are driven by suitable reduction gearing. helical gears and are oppositely arranged so as to counteract driving thrusts thereon axially of the gears. The gears 47 are driven by a pair of gears 48 mounted for rotation on a common shaft with a herringbone gear 49. The gear 4? is driven by a herringbone gear 50 which, in turn, is

and snugly fit the bearing bloclr 60 which remains at all times mounted on the turntable 45.. By this-arrangement the bearing block 60 can be supported effectively by the Preferably the gears 47 are driven by an output shaft 51 of a speed reducing transmission 52. The input shaft 53 of the transmission is driven by a suitable electric motor 54, for example, a 150 hp. 'D.C. motor of 300 to 1200 r.p.m., with a gear reduction such that the table turns about 0.03 rpm. T he gears 47 are driven also by additional sets of gears, the

parts being the same as those heretofore described and 1 designated by the sufiix a.

At its opposite end, the turntable 45 is mounted in a suitable bearing block which is adapted who received,

in an upright movable bearing support 61. The bearing support 61 is mounted on a trackway 62, which is parallel to the tracks of the carriage 10, for sliding endwise parallel I to the path of the carriage. For moving the upright bear-s ing support at along its trackway, it is provided with .a dependent internally threaded follower 63 which engages a rotatable worm shaft 64. The shaft 64 is driven in opposite directions selectively,by a reversible motor 65.

The upright support 611 is in the form of a C-clamp with support ohyet thesupport can be removed for purposes of removing formed stock. from the turntable in a direction parallel to the .axis of the turntable. However, the bearing block 60 must be fixedly secured in place. in the socket during the stretch forming operation. For this purpose, a heavy duty clamping arm 67 is pivotally mounted on a pivot 68 on the support 61 and is adapted to close the open side of the C-clarnp 65 and engage the face of the block 60 exposed at the open side. The arm 67 carries at its upper end a locking portion 69 which is adapted to enter the socket 66 and engage a portion of the top of the bearing block 60. A suitable reversible pneumatic piston and cylinder. assemblage 70, including the cylinder 71, piston 72, and piston rod '73, is provided for moving the rocker arm 6710 clamping position wherein the locking portion 69 is within the (Z-clamp. The piston rod 73 is connected to a rocker arm 74 which is rigid with the arm 67.

In order to lock the locking portion 69 in position when it is in the G-clamp, a piston and cylinder assemblage '75, including a reversible pneumatic cylinder 76 and a piston 77 with a rod 78,.is mounted on the upright portion 61. The rod 78 carries at its lower end a detent '79 which is receivable in an upwardly open notch 80 in the locking portion 69 when the arm 67 is in clamping position. The detent 79 may be mountedin suitable guideways 81 in the support 61. With this arrangement the bearing block 6% can be held fixedly inthe proper position during forming, and after the forming operation the locking portion 65 may be released and the upright support s1 driven away from the operating position or to the left in FIG. 5 by the motor 65, thus affording access endwise to the turntable 45.

The turntable, as mentioned, preferably is in the form of a rigidfour-sided shaft having a plurality of longitudinal T-slots 83 distributed on its surface. A side face die 84 may be provided, coextensive with the length of the table between the bearings, if desired. Preferably the die 34 comprises a plurality of die segments 84a having at their inner surfaces suitable T-portions 85 receivable in the T-slots 83. The segments maybe such that each one fits a different face of the shaft orturntable 45. One section is provided with a gripping jaw 86 coextensive with the length of the turntable axially and arranged to grip the end of a length of stock S which is to be wrapped on the die.

In the form illustrated in FIG. 4, the die is one which is circular. However, as illustratedin FIG. 8, the die, indicated at 37,, maybe of such other shape as the requirements of the finished piece demand.

The structure is operated through the conventional cycles during the forming operation. However, it is to be appreciated that very heavystresses are developed. For instance, in the form. illustrated, the stock width is 16 feet, the tension is 1,000 tons, and the diameter of the die is 7 feet, 8 inches.

The apparatus may be operatedby manual control or automatic control in the well known manner, the only difference from the conventional operation being that after the forming of the length of stock the bearing sup-,

port 61 is removed from the bearing block 60 and out of alignment with the end of the turntable. vIt is to be noted that the bearing portion of the turntable is not removed from the bearing block 60. Instead the bearing portion remains in the block 60 at all times, as distinguished from a conventional split-bearing type of mounting. Thus, precise mounting of the turntable in its bearing block is maintained during operation and during removalof the support 61.

. The clamping head 30 is provided with suitable wedge jaws 88 andbft having outer Wedge surfaces cooperable with the wedge. surfaces 90 in the head. The jaws are moved along the wedge surfaces by rods 91 of pistons 92 of reversible hydraulic piston and cylinder assemblages 93, an example of which is described in the copending application of Cyril J. Bath, Serial No. 173,310, filed February 14, 1962, issued as US. Patent No. 3,116,780, granted January 7, 1964.

Having thus described my invention, I claim:

1. A stretch forming machine comprising an elongated frame, an upwardly facing trackway on the frame, a die support mounted on the frame at one end of the trackway for rotation about a horizontal axis extending transversely of the length of the trackway, a power operated gripper carried by the die support for gripping one end of a length of stock which is to be stretched about a die on the support, a carriage mounted on the trackway for movement therealong endwise thereof, a stretch head supporting arm mounted on the carriagefor rocking about a horizontal axis parallel to the rotational axis of the support, said arm having a portion extending from the rocking axis of the arm endwise of the trackway toward the support, a stock gripping head carried on said portion of the arm in spaced relation to the rocking axis and adapted to grip the other end of the length of stock for applying tension to the stock endwise of the stock by concurrent rotation of the support and controlled travel of the carriage along the trackway, driving power means connected to the support for rotating the support, stretch forming power means connected to the carriage for controlling the movement of the carriage along the track- Way so as to tension the stock into a range above its elastic limit as the stock is Wrapped onto a die on the support, counterbalance means connected to the arm and operative to move the arm and thereby the stretch head upwardly away from the track to a predetermined position and to hold the head yieldably in said predetermined position, and said counterbalance means being adjustable for changing the counterbalancing force applied to the arm.

2. A stretch forming machine comprising a frame,

an elongated upwardly facing trackway on the frame,

a rotary die support having a die supporting portion between its ends,

coaxial bearing means on the frame spaced from each other transversely of the length of the track near the endwise projected lateral limits of the trackway, respectively, and connected to the ends of the die support and rotatably supporting the die support, with the die supporting portion between said endwise projected limits, for rocking about a horizontal axis extending transversely of the length of the tracka carriage mounted on the trackway for rolling therealong and having a stretch head supporting portion disposed between the lateral limits of the trackway,

roller means on opposite sides of the carriage engaging the trackway near the lateral limits of the trackway and constraining the carriage to move in a lineal path parallel to the trackway toward and away from the die support,

a stretch head support mounted on the carriage between the lateral limits of the trackway for rocking about a horizontal axis parallel to the axis of the die support, and extending forwardlyjrom the carriage toward the die support, a stretch head on the forward end of the stretch head support,

gripper means carried by the die support and by the stretch head, respectively, for gripping onto opposite margins of a length of stock for applying tension thereto, counterbalance means connected to the stretch head support and operative to rock the stretch head support about its axis and thereby move the stretch head upwardly away from the track to a predetermined position and to hold the stretch head yieldably in said predetermined position,

power driving means for rotating the die support, and

power operated tensioning means for controlling the movement of the carriage toward the support for tensioning the stock above its elastic limit.

3. A stretch forming machine comprising an elongated frame, an upwardly facing trackway on the frame, a die support mounted on the frame at one end of the trackway for rotation about a horizontal axis extending transversely of the length of the trackway, a power operated gripper carried by the die support for gripping one end of a length of stock which is to be stretched about a die on the support, a carriage mounted on the trackway for movement therealong endwise thereof, a stretch head supporting arm mounted on the carriage for rocking about a horizontal axis parallel to the rotational axis of the support, said arm having a portion extending from the rocking axis of the arm endwise of the trackway toward the support, a stock gripping head carried on said portion of the arm in spaced relation to the rocking axis and adapted to grip the other end of the length of stock for app-lying tension to the stock endwise of the stock by concurrent rotation of the support and controlled travel of the carriage along the trackway, driving power means connected to the support for rotating the support, stretch forming power means connected to the carriage for controlling the movement of the carriage along the trackway so as to tension the stock into a range above its elastic limit as the stock is wrapped onto a die on the support, counterbalance means connected to the arm and operative to move the arm and thereby the stretch head upwardly away from the track to a predetermined position and to hold the head yieldably in said predetermined position, said counterbalance means comprising a bracket means rigid with the arm and having a portion extending to the opposite side of the rocking axis from said portion of the arm, and Weights carried by the bracket means in spaced relation to the rocking axis.

References Cited by the Examiner UNITED STATES PATENTS 823,766 6/06 Conklin 15335 2,441,858 5/48 Watter 15335 3,017,916 1/62 Nasvytis 153-40 CHARLES W. LANHAM, Primary Examiner.

WILLIAM J. STEPHENSON, Examiner. 

1. A STRETCH FORMING MACHINE COMPRISING AN ELONGATED FRAME, AN UPWARDLY FACING TRACKWAY ON THE FRAME, A DIE SUPPORT MOUNTED ON THE FRAME AT ONE END OF THE TRACKWAY FOR ROTATION ABOUT A HORIZONTAL AXIS EXTENDING TRANSVERSELY OF THE LENGTH OF THE TRACKWAY, A POWER OPERATED GRIPPER CARRIED BY THE DIE SUPPORT FOR GRIPPING ONE END OF A LENGTH OF STOCK WHICH IS TO BE STRETCHED ABOUT A DIE ON THE SUPPORT, A CARRIAGE MOUNTED ON THE TRACKWAY FOR MOVEMENT THEREALONG ENDWISE THEREOF, A STRETCH HEAD SUPPORTING ARM MOUNTED ON THE CARRIAGE FOR ROCKING ABOUT A HORIZONTAL AXIS PARALLEL TO THE ROTATIONAL AXIS OF THE SUPPORT, SAID ARM HAVING A PORTION EXTENDING FROM THE ROCKING AXIS OF THE ARM ENDWISE OF THE TRACKWAY TOWARD THE SUPPORT, A STOCK GRIPPING HEAD CARRIED ON SAID PORTION OF THE ARM IN SPACED RELATION TO THE ROCKING AXIS AND ADAPTED TO GRIP THE OTHER END OF THE LENGTH OF STOCK FOR APPLYING TENSION TO THE STOCK ENDWISE OF THE STOCK BY CONCURRENT ROTATION OF THE SUPPORT AND CONTROLLED TRAVEL OF THE CARRIAGE ALONG THE TRACKWAY, DRIVING POWER MEANS CONNECTED TO THE SUPPORT FOR ROTATING THE SUPPORT, STRETCH FORMING POWER MEANS CONNECTED TO THE CARRIAGE FOR CONTROLLING THE MOVEMENT OF THE CARRIAGE ALONG THE TRACKWAY SO AS TO TENSION THE STOCK INTO A RANGE ABOVE ITS ELASTIC LIMIT AS THE STOCK IS WRAPPED ONTO A DIE ON THE SUPPORT, COUNTERBALANCE MEANS CONNECTED TO THE ARM AND OPERATIVE TO MOVE THE ARM AND THEREBY THE STRETCH HEAD UPWARDLY AWAY FROM THE TRACK TO A PREDETERMINED POSITION AND TO HOLD THE HEAD YIELDABLY IN SAID PREDETERMINED POSITION, AND SAID COUNTERBALANCE MEANS BEING ADJUSTABLE FOR CHANGING THE COUNTERBALANCING FORCE APPLIED TO THE ARM. 